Having hold luggage isn't really a factor at all in SNN - you just get shown your bags on a computer screen and have to confirm they are yours. You don't have to actually do anything with them.
As someone else has said - it's at JFK that not having hold luggage can be really neat. Because BA1 arrives into JFK as a 'domestic' flight, you walk off the plane and right into the terminal. You can be through the baggage belt in about 3-5 minutes, but your bags almost certainly take 10-15 minutes longer. If you can hand baggage and just walk out, so much the better.
Last time I did this, I was on the Airtain cruising past the BabyBus before the flight crew had even left the cockpit (I could see them!) - literally 6-7 minutes after walking away from my seat.